This invention relates to an optical curing system and more particularly relates to a light guide coupling apparatus suitable for coupling a light guide to a light source for optical curing purposes.
Some resins commonly referred to as UV resins will transform from a tacky substance to a tack-free form upon being subjected to optical curing by ultra violet light in the range of from 200 nanometer (nm) to 400 nm. Such curing technique is particularly advantageous in the formation of resinous base adhesive on a substrate or medium. The adhesive coating thus formed on the substrate is extremely strong and has a high strength bonding to the substrate. The curing process can be completed in a very short time of less than a minute, in comparison with a day or more with the use of other conventional curing methods such as heat curing. Moreover, since no heat is involved in the optical curing process, no heat damages will occurred to the substrate or other delicate components which may be located in the immediate area on the substrate at which the resin is to be cured in situ or on-the-spot. For the above reasons, optical curing of UV resins used as adhesive lends it particularly useful in the fabrication process of making such as fibre optic joints, electro-optics, lens assembly, printed circuit board applications, wire tacking, encapsulating or potting, and high strength bonding of disparate materials.
In order to carry out the optical curing process on-the-spot or in situ in a work piece, the ultra violet light generated by a light source must be directed by a light guide commonly referred to as a light wand and normally made of a fluid light guide such as an elongated optical fibre, to illuminate at the spot or area in the work piece having the UV resin provided thereon. However, due to the inherent infra red radiation present in the ultra violet radiation, which invariably creates harmful heat in the light guide, as well as the close proximity of the light guide to the hot housing of the ultra violet lamp, the high temperature can cause damage to the light guide. In some known optical curing devices thermal protection for the light guide are provided by incorporating heat absorbing filters located between the light guide and the lamp. However, the filtering lens also invariably attenuates the desirable useful light radiation. The attenuation of the light radiation by the filtering lens grows quickly to unacceptable high values at wavelengths below 340 nm which are essential in the optical curing of adhesive.